I am trying to create a private network on docker such that each geth node in the network is run on a docker container.

I followed this git hub blog :https://gist.github.com/fishbullet/04fcc4f7af90ee9fa6f9de0b0aa325ab . I am able to create containers and run geth nodes but the nodes always show hashrate=0.It take a lot of time to mine even if the difficulty in the genesis file is set to very low value(0x10). I thought it is the geth version problem.Will it work if I downgrade geth to lower version ??

On which nodes are you trying to mine? The creation of the DAG ethereum.stackexchange.com/questions/1993/… is a very space and cpu consuming task. So, if the nodes you are deploying your network are not powerful, this task requires a lot of time. The dag does not depend on the difficulty as you can read in the yellow paper.
– BriomkezJun 4 '18 at 17:27